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Electrical Engineering
Electrical engineering is a field of engineering that deals with the study and application of electricity, electronics and electromagnetism.
23,056 Questions
Why the output voltage drop when the load current is increase?
As the load current increases the losses in the circuit increases (I2R loss) and speed of the generator decreases so the voltage falls a little. and this voltage fall can be adjusted by increasing the speed of the generator and Iron losses are taken as constant losses.
Why does one bulb make the others go out in a series circuit?
because current in parellel divides unlike in series if one fails all will fails
AnswerThe parallel circuit's load current doesn't 'divide'. It's the other way around! Each branch draws an individual current which then 'combine' to form the circuit's load current. However, the reason that the remaining lamps connected in parallel always work, even if one fails, is because each branch of a parallel circuit is subjected to a common supply voltage.
What is the relationship between capacitors in series and resistors in series?
resistor isdefined as the opposing the current flow in a circuit. capacitor is defined as the store the electric field in one forth of the cycle and the another quarter cycle stored energy will be released
The temperature of the sun's corona reaches at least one million degrees and possibly more. This is strange because the surface of the sun has temperatures of five thousand degrees. The corona is much farther away and logically should be cooler.
The total resistance is 5 ohms. Scroll down to related links and look at "Parallel Resistance Calculator".
Can 60hertz transformer use at 50hertz power?
As long as they're the same voltage, yes it will, but probably not for long. A lot depends on what type of appliance you're using. For instance, if it's an electric stove, you'd probably be OK, but if it has a clock, expect it to run slow. And even that too, dependfs on what type of electric stove it is. The problem is that at the lower frequency, the device has to draw more power in able to do the same amount of work that it would at 60 Hz. Because of that, some motors, electronically controlled devices and the like, tend to overheat as a result. For a window fan, it's probably no big problem (although I'd keep an eye on it until I knew for sure) but for something that's `frequency dependent', like a refrigerator compressor, I'd think you'd just be asking for problems. Usually during the day, voltages and frequency of the U.S. system varies in both frequency and voltage. A `brown-out' usually happens when the voltage falls below 80 volts, as compared to the nominal 117 volts. But too, so does the frequency. Tis is mainly because of industrial usage during the day, along with air conditioners and the like. Late at night though, it's usually closest to where it's supposed to be. Does it work? Will it work? Yes. The question is: For how long.
What is no load current in transformer?
I'm not sure that it is correct to say a transformer limits current under no load (maybe it is, depending on your application).
A step down transformer converts a high voltage at the primary to a lower voltage at the secondary. Under no load conditions, the secondary will be an open circuit. Since The primary current relative to the secondary current will be Np/Ns (the turns ratio, primary to secondary), and the primary voltage relative to the secondary is Ns/Np, the apparent resistance at the primary due to an open at the secondary will be (Np/Ns)^2*(open circuit). Since an open circuit is typically approximated as an infinite resistance, resistance is infinite. The turns ratio in this idealized example doesn't really matter, hence the transformer doesn't really matter (only the fact that a no load means an open secondary matters).
How can be three phase transformers connected in parallel?
It is common to pull parallel conductors to a transformer when the expected current is high enough. It can become difficult to pull 400A and larger wire so you can use 2,3 or 4 sets of smaller parallel wires to accomplish the current.
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Transformers are frequently connected in parallel with each other in order to increase the amount of apparent power (expressed in volt amperes) they can supply to a load.
What is meant by parasitic capacitor?
Parasitic capacitance is the unwanted capacitance between:
1. A signal line and other signal line.
2. A signal line and earth.
3. A signal line and power supply line.
Not that, I remember all (even most) of the effects, let me answer you with whatever I remember:
1. Unwanted coupling between two different signals, resulting in "crosstalk" between two signals. One signal interferes with other and other interferes with one.
2. attenuation / distortion of high frequency signals which have high impedance / limited current capability.
3. Ringing (unwanted oscillations) rising edge and falling edge of the signals rectangular / square wave.
Advantages of transistors over triode?
Transistors are sometimes referred to as semiconductor triodes.
OK, but to answer the question:
Vacuum-tube triodes need some hundreds of milliwatts to watts just to light the filament/heater. This is wasted power that can appear as waste heat in the circuit, and reduces the electrical efficiency of the vacuum-tube triode. Triodes also have limited lifetimes, commonly due to the filament/heater burning out, or losing its electron emission. Transistors have no such limitations and are (i) much more efficient, (ii) can run at much lower power, and (iii) have very long lifetimes.
Vaccuum-tube triodes cannot be made much smaller than around 10 mm/half an inch in diameter, and maybe the same length. Transistors can be made at the nanometre scale, so transistor electronics are much more compact. Imagine putting together a USB memory chip with (at least) 32,000,000,000 triodes!
Conventional triodes are able to operate to about 5 GHz (5000 MHz). Some special valves can work at higher frequencies, about around 100 GHz is the limit. Such valves are large, expensive, and have high noise figures. Low-noise, small, cheap transistors exist that can easily work past 100 HGz.
The emitter bypass capacitor, in a typical common emitter configuration, increases gain as a function of frequency, making a high pass filter. Removing the capacitor will remove the gain component due to frequency, and the amplifier will degrade to its DC characteristics.
Are the voltages across all branches of a parallel circuit the same?
In a parallel circuit, all the branches are joined together at their start and again at their end by a conductor (usually wire).
Now, the surface of a conductor (ideally) is an equipotential surface. That is, any point of its surface has the same electric potential.
And since the voltage across each branch equals the difference in electric potentials between its start and its end, and these potentials are the same for every branch, it follows that the voltages across each branch must be equal to each other.
Why ohm's law is not applicable in networks?
Ohm's Law: Volage = Current times Resistance Yes, voltage is proportional to current. That applies in simple circuits as well as to complex circuits such as electrical networks. Your statement that "voltage is inversely proportional to current in electrical circuits" is incorrect. Perhaps you are not considering some critical part of the statement, or you simply heard it wrong.
How do you test chopper transformer?
A chopper transformer is a kind of transformer used in an switching power supply.The primary input voltage of it is a Direct current (D.C) unlike any other ordinary step down transformer which uses an Alternating Current (A.C).Chopper transformer uses a switching transistor to produce a secondary voltage..
Electrical current is a fascinating and powerful tool. It can be both safe and deadly: the emissions from a Tesla coil, while awe inspiring, pass harmlessly around and through humans; yet, ramp up the current enough, and severe effects can occur.
The major factors that affect a person are: the amount of current, measured in amperes or "amps"; the path the current takes through the body (i.e. through the heart); and the length of time the body is exposed as a circuit.
The voltage, environmental moisture, whether the heart is in a beat or not, and the person's health can also affect the severity of the shock. The following list details effects of current. Note that 1000 milliamperes (mA) equates to 1 ampere (A).
1 mA of current causes a bit of a tingling sensation, but can be dangerous under some conditions.
5mA of current results in a slight painless shock. Strong involuntary reactions can cause injuries to the person.
6-16mA results in a painful shock, and the individual is less likely to have control over their muscles.
17-99mA results in extreme pain, respiratory arrest and strong muscular contractions. Death is quite probable at this point.
100mA-2A results in uneven, uncoordinated pumping of the heart. Nerve damage begins here. Death is highly likely.
At more than 2 amperes, the heart stops, internal organs begin to cook, and sever burns occur. Death is quite probable without immediate medical assistance.
See the related links below for further details.
What must be applied to an electric charge to make it flow in a circuit?
There are many complex explanations for current flow in electronics. The answer below describes the basic requirements without including great detail. For a more academic discussion, you are advised to look at relevant sections of text books on electrical and electronic engineering.
In order for electrical current to flow, there must be two things:
1) A voltage (sometimes referred to as a "potential difference"). The voltage can be created by a battery, a generator, a solar cell or a mains voltage outlet.
2) A complete circuit. This must include conductors such as wires that start at the positive terminal of the voltage source and at the far end, return to the negative terminal of the voltage source. Other components such as lamps, resistors and switches can form part of the complete circuit.
We must have a voltage for current to flow because without it, there is no "electrical force" to cause the current to flow.
We need a complete circuit so that the current can flow from the positive of the voltage source, through conductors and return to the negative of the voltage source. Current will flow through any complete circuit. If a switch is part of the circuit, when it is open, no current can flow because the circuit has been broken. When the switch is closed, the circuit is complete and current will flow once again.
Therefore, it is possible to have a voltage without a current (switch open, for example) but it is not possible to have a current without a voltage.
NB: Mains electricity is alternating current. It follows the same principles as the DC examples mentioned above although there is a changing voltage rather than a constant voltage.
What is the difference between radio frequency and audio frequency?
They terms frequency are essentially the same, except radio waves are electromagnetic, and acoustic waves are pressure waves. An audio frequency is a range of frequencies that we can hear, approx up to 20Khz, anything past 20Khz is said to be radio waves
In a parallel circuit is the current is shared between the loops?
The current splits, part of it goes through each of the separate branches, then it gets back together again.
This answer is misleading.
What actually happens is this. Each branch draws a current which is determined by the supply voltage divided by the resistance of that branch. The sum of these branch currents is then drawn from the supply.
So, the current doesn't actually 'split', but is the sum of the individual branch currents.
How do you test a capacitor using a multimeter?
A cheap multimeter can be used to test if a capacitor is burnt out. Connect one lead of the capacitor to one lead from a resistor (about 50k ohms). Set the multimeter to a high "ohms" setting and place the test leads on the remaining cap and resistor leads. The display should begin at 50 KOhms and then get higher and higher until it reads infinity/overload.
A bad capacitor will either start at infinity/overload or start at 50KOhms and stay there. It won't tell you the ferad rating of the capacitor, but it will give a starting point to troubleshoot.
What if two current source connected in series?
Theoretically not allowed and practically not safe or desirable to have two current sources in series or two voltage sources in parallel. In practice, the sources will get hot and catch on fire -- very unwise to even try.
Why only 50 hz frequency is used in India?
It may be one of the following reasons:
- It may In US, the frequency is 60Hz and 110V supply, but in India is about 240V, 50Hz supply. For a particular load say 100kW the current will be 0.416A. But in US the same load will consume about 0.9A. Here the thing is the heat produced in the cable because of the flow of current will be large in US compare to India. Since US is a cold country they can use this level but not in India.
- Moreover, once standardisation is fixed for Indian (50Hz) by British, so its continuing and in America its 60 Hz according to their standardisation.
- Its only because, too low value will create fluctuation in apparatus like Bulb starts blinking(persistence of eye is 15 Hz) and too high value will lead more hysteresis and eddy current losses in many machines.
What is the leakage current of a conductor?
A: Transistor like any diode leaks a very small current. This leakage is specified as Ico tested with the base open. Manufacture specification sheets will have this information for each device that they manufacture.
What is the definition of operating point of diode?
The current you set it to work at. Using for example resistors you can set the voltages and currents at a certain DC level. At that point the transistor will work. It is mostly (but not always) used to put the transistor in its linear region.
